Conventional systems for packaging electrical components have consisted of separate structures: first, a vertical cabinet including a frame and vertical mounting rails attached along the front sides of the frame; and second, subframes or subracks holding electrical components and adapted to slide within the main frame. Typically, the subframe, such as a "card cage," occupies a significant amount of space along the interior sides of the main frame, space which therefore cannot be used for the storage of the electrical components themselves. For example, a standard card cage designed to fit into a standard 19 inch vertical cabinet has only 16.8 inches of usable width for circuit boards.
One prior art frame/subframe system is shown in U.S. Pat. No. 3,868,158. A rack is provided for the mounting of connection boxes filled with printed circuit cards. More than one box can be inserted side by side in a row. Thus, valuable space is occupied by subframe sides at multiple locations between the sides of the main frame.
An adjustable card cage or cabinet for storage of cards is shown in U.S. Pat. No. 4,277,120. Circuit boards are retained between modular retaining members which allow simultaneous storage of boards having differing widths. It is stated that the cabinets are structurally arranged and have sufficient structural strength to permit stacking of multiple units for the purpose of storing unused circuit boards.
Thus, there has been a need in the art to provide a packaging device for electrical components and systems which avoids using space for non-productive subframes such as card cages, and is capable of greater versatility in mounting electrical components.